Protozoa Flashcards
How are Protozoa classified?
Kingdom Protista - eukaryotic
What type of cell are Protozoa?
Single celled animals (unicellular).
Are all Protozoa pathogenic?
No. Most are free-living and non-pathogenic.
Are Protozoa parasitic?
They can be.
What is the anatomy of Protozoa?
-Nucleus
- Membrane-bound nucleus (eukaryotic)
What is the anatomy of Protozoa?
-Locomotion
- Pseudopodia
- Cilia
- Flagella
Pseudopodia
- False feet.
- Cells have NO definite shape.
- Amoeba
Cilia
- Tiny hair-like projections that cover the entire body, or just part (one side).
- Found ONLY in trophozoite stages.
- Ciliates
Flagella
- Long whip-like structures.
- May be one or several, ONLY found in trophozoite stages.
- Flagellates
Are Protozoa sexual or asexual?
May be either, or they may alternate between the two.
Asexual reproduction in Protozoa.
- Sometimes by binary fission.
2. Sometimes by schizogony.
Schizogony
3 Stages
- Multiple fission.
- Undergoes multiple mitoses to form a multi-nucleated schizont.
- Schizont bursts and releases multiple new organisms (merozoites).
What two things do most Protozoa have?
Most have two morphological forms.
- Trophozoite
- Cyst
Trophozoite
- This is the feeding and reproduction stage.
- Live and reproduce inside the host.
Cyst
- Dormant stage.
- Survives in the environment.
- Infective to new host (usually by ingestion)
Which morphological form of Protozoa are the diagnostic form?
Cysts
-They come out in the feces.
Which morphological form of Protozoa do we not usually see?
Trophozoite
What is the common life cycle of Protozoa?
- Host ingests cyst.
- In host, cyst undergoes excystment.
- Develops into trophozoites in host body.
- Usually, trophozoites encyst before leaving the host body.
- Therefore, new cysts enter the environment and wait to infect a new host.
- Some life cycles get more complicated.
What does excystment mean?
Organism comes out of, or EXITS, the cyst and starts to grow.
What does encystment mean?
Organism forms, or ENTERS into, a new cyst.
What are the 4 subphyla of Phylum Sarcomastigophora?
- Sarcodina
- Ciliaphora
- Mastigophora
- Apicomplexa
What are Sarcodina called?
Amoebas
What do Amoebas look like?
No defined shape.
How do Amoebas feed and move?
By pseudopodia.
Where are Amoebas common?
They are common in water and most soil. Most of them do NOT cause disease.
What are the 4 steps in the life cycle of Amoebas and Ciliates?
- Cysts are ingested by drinking fecal contaminated water, or ingesting fecal contaminated material.
- Excystment in intestines produces trophozoites.
- Trophozoites reproduce by binary fission inside the host.
- Trophozoites and cysts are shed in feces.
What happens to trophozoites and cysts after they have been shed in the feces?
- Trophozoites die very quickly in the environment.
- Cysts survive to infect another animal.
What disease to Amoebas cause?
Amebiasis
What is one example of an Amoeba that can infect animals?
Entamoeba spp.
What are Ciliaphora called?
Ciliates
What do Ciliates do in the trophozoite stage?
Use cilia for locomotion and/or feeding.
What is it rare to see in the feces with Ciliate infection?
Cysts
What is usually seen in the feces with Ciliate infection?
Trophozoites
How is Ciliate infection dx’ed?
Presence of trophozoites in the feces.
What do you have to do to see trophozoites when Ciliates are suspected?
- MUST use fresh stool sample since trophozoites die quickly.
- May have to use direct smears instead of fecal floatations.
What one example of a Ciliate that can cause infection in animals?
Balantidium coli
What are Mastigophora called?
Flagellates
-mastigophora means whip-bearer.
What do flagellates posses?
They are protozoa that posses at least one long flagellum.
What is the flagellum normally used for?
Movement
Are all flagellates alike?
No.
- They are highly variable in shape and life cycle.
- About the only thing they have in common is flagella.
What are the 2 types of parasitic flagellates?
- Hemoflagellates
2. Mucosoflagellates
Where do Hemoflagellates live?
In the blood, lymph, and tissue fluid.
How are Hemoflagellates usually transmitted?
Blood-sucking insects.
Are Hemoflagellates important in veterinary medicine.
No
What do Trypanosomes cause in humans?
Sleeping sickness.
Where do Mucosoflagellates live?
Digestive or genital tract.
How are Mucosoflagellates transmitted?
Feces or genital fluid.
Are Mucosoflagellates zoonotic?
Yes
What is one example of Mucosoflagellates?
Giardia spp.
Infective forms of Apicomplexa are characterized by?
An ornate complex of organelles at their apical ends.
The most complex and diverse group of Protozoans is?
Apicomplexa
Do Apicomplexa have complex or simple life cycles?
They all have complex life cycles.
What is another name for Apicomplexa?
Sporozoa
What are sporozoites?
Nonmotile cyst-like shapes. They look like commas inside an oocyst.
What is the infective form in Apicomplexa?
Sporozoites
What are all Apicomplexa parasites of?
Animals
What are the most important veterinary parasites?
Coccidia
Where do Coccidia usually grown in the host?
The intestines.
Coccidia cause a form of enteritis called?
Coccidiosis
How is Coccidia transmitted?
Fecal-oral route.
What are 6 examples of Coccidia?
TBS ICE
T oxoplasma gondii
B abesia canis
S arcocystis spp.
I sospora spp.
C ryptosporidium spp.
E imeria spp.
TYPICAL COCCIDIA LIFE CYCLE
Where do the sporozoites live in the host?
The intestines.
TYPICAL COCCIDIA LIFE CYCLE
What does the sporozoite grown into? What does this form look like?
A trophozoite. These are amoeboid looking.
TYPICAL COCCIDIA LIFE CYCLE
How do trophozoites reproduce?
By schizogony to produce many merozoites.
TYPICAL COCCIDIA LIFE CYCLE
What is schizogony?
Multiple division within the cell. The cell bursts and releases many merozoites.
TYPICAL COCCIDIA LIFE CYCLE
What do merozoites look like?
Comma, or banana shaped.
TYPICAL COCCIDIA LIFE CYCLE
What do merozoites do?
Escape the host cell and enter other host cells in the intestines. They lyse the host cell in the process.
TYPICAL COCCIDIA LIFE CYCLE
After the merozoites invade a new cell, what do they do?
Divide more and form male and female gametocytes.
TYPICAL COCCIDIA LIFE CYCLE
What do the gametocytes do?
They fuse to form zygotes.
TYPICAL COCCIDIA LIFE CYCLE
What do the zygotes do after they have been formed by the gametocytes?
Produce sporozoite-filled oocysts.
TYPICAL COCCIDIA LIFE CYCLE
What happens to the oocysts after the zygotes produce them?
They are excreted from the host in the feces.
TYPICAL COCCIDIA LIFE CYCLE
After the oocysts have been excreted in the feces, what happens to them?
They are ingested by the new host.
TYPICAL COCCIDIA LIFE CYCLE
Do all coccidia complete their life cycle in one host?
No. Some require 2 hosts.
What is Entamoeba histolytica?
Coccidia that are Sarcodina (amoebas).
What does Entamoeba histolytica do?
Causes intestinal amebiasis (amebic dysentery). AKA: montezooma’s revenge
What are the hosts in Entamoeba histolytica?
- Mainly dogs.
- Also infects cats, humans, and others.
In what host is Entamoeba histolytica the most serious?
In humans.
Are Entamoeba histolytica host specific.
No
Where is Entamoeba histolytica usually found?
In water (ponds, streams) and moist soil.
What does Entamoeba histolytica do to the host?
Damages intestines and causes ulcers in the colon.
What are the symptoms of Entamoeba histolytica?
Diarrhea with abdominal pain, blood in the stool.
Is Entamoeba histolytica zoonotic?
Occasionally. Most of the time dogs, and cats catch it from humans. Fecal-oral.
How is Entamoeba histolytica diagnosed?
By finding cysts or trophozoites in the feces (mostly cysts).
What may you need to do to find trophozoites in Entamoeba histolytica infection?
Use direct smear instead of fecal float, since they do not survive well outside the host.
What is Balantidium coli?
Coccidia that are Ciliaphora (ciliates).
What is the importance of Balantidium coli?
It is the only really important ciliate.
How big is Balantidium coli?
Very large, 30-150 micrometers.
What is the host for Balantidium coli?
- Humans
- Pigs
- Other animals